Elongated to connect parts of body – elongated bits covered by insulating myelin sheath to increase speed of impulses – have branched endings so can act on many muscle fibres or connect with other neurones

Elongated parts carrying impulses away from cell body = axons

Elongated parts carrying impulses to body = dendrons

–sensory neurones – take impulses from stimulated receptors in sense organs to the CNS

·Alcohol is a depressant that contains the chemical ethanol – Physical effects: short-term use can blurred vision long-term use can lead to damage to the brain and liver (cirrhosis). The liver removes alcohol from the body excess use can lead to unconsciousness, brain damage, coma and death. Mental effects – increase reaction times by slowing down the synapses, can cause depression and can lead to loss of inhibitions and self-control.

·

Tobacco contain tar and nicotine and produces carbon monoxide when smoked – carbon monoxide is absorbed by haemoglobin in red blood better than oxygen long term use can lead to: emphysema ( alveoli walls break down), build up of mucus cilia stop moving, bronchitis, damage to circulatory system, cancer and increased heart rate and blood pressure and blood pressure because of nicotine narrowing blood vessels

Cancer

These cause cells to mutate and divide uncontrollably, which can form cancerous tumours.

Smoking and poor health

Studies show that smoking shows a direct correlation with poor health especially with lung cancer

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Plant hormones

·Plants are sensitive to light and gravity (shoots grow towards the light and roots towards the light/phototropic and gravitropic)

·The two most important hormones are called auxins and gibberellins: auxins promote cell elongation and gibberellins promote cell elongation and encourage flowering, breaking seed dormancy and can be used to force seedless fruit to develop.

Gravity

Hormones in solution travel down towards the lower sides of shoots and roots;

·In the shoots, auxins increase growth in the lower region, which makes the shoot bend upwards.

·In the roots, the hormones slow down the growth in the lower region, which makes the root bend downwards.

Light

in shoots, light causes auxins to accumulate on the shaded part of the stem , which causes growth on that side and means that the plant grows towards the light.

Commercial uses of plant hormones

·Gardeners often apply selective weed killers (with a hormone that kills everything but grass) to their lawns.

·You can place stem cuttings in rooting powder to promote formation of roots so you cake make many identical plants from on original.

·Fruit gets sprayed with unpollinated flowers with gibberellins so they make fruit faster.